Radiation-induced synthesis of hydrophobic cryogels with rapid and high absorption of organic solvents and oils

Herein, for the first time, macro-porous hydrophobic cryogels of poly( iso- decyl acrylate- co -ethylene glycol dimethacrylate) P(IDA- co -EGDMA) have been successfully fabricated through γ -ray radiation-induced cryo-polymerization. This synthesis route is highly advantageous over the reported redox and UV-radiation routes for the synthesis of hydrophobic cryogels considering the high energy and the penetrating depth of γ -ray, which favours the fabrication of larger cryogels within shorter duration. The effects of radiation time, dose rate, amount of cross-linker, solvent type and solvent amount on the cryo-polymerization were studied in detail, which were based on the measurements of gel fraction and contact angle as well as the characterizations of Fourier transform infrared spectroscopy , thermal gravimetric analysis and scanning electron microscopic examination. The fabricated macro-porous cryogels were used as a sorbent for different organic solvents and oils. Using benzene as a common organic solvent, the absorption equilibrium was reached within only 60 s and the absorption capacity varied in the range of 16–20 g/g depending on the cryogel morphology and crosslinking density. As for the halogenated solvents, P(IDA- co -EGDMA) cryogels absorbed 25–29 g/g of chlorobenzene, bromobenzene, iodobenzene and tetrachloromethane. Those cryogels withstood high temperature (150 °C) deprived of any alteration in absorption capability and pore morphology. The cryogels reusability was also confirmed with keeping absorption capacity and cryogel mass up to 10 cycles.